The picture on the left is a "corral" of iron atoms, arranged in a circle by hand (actually using a scanning tunnelling electron microscope. The corral is around one billionth of a meter across. The circular ripples inside the corral are electron waves, which show that at the microscopic levels, particles such as electrons are not localised. This picture, in addition to being a technological marvel, is striking verification of the bizarre predictions of quantum mechanics, the theory known to accurately describe the world of atoms and electrons.
The picture on the right was taken by the Hubble space telescope. It shows the accretion disk of a monstrous back hole at the core of a galaxy many light years away.
This picture too is a technological marvel, taken by a telescope in orbit around the Earth, and provides beautiful support for the existence of black holes, which are among the more bizarre predictions of Einstein's theory of gravity, or general relativity as it is known by scientists. General relativiy is known to accurately describe the dynamics of very massive, large gravitating objects.
It is an amazing circumstance that the two physical theories graphically represented on this slide are in fact not compatible with each other. If one applies the rules of quantum mechanics to Einstein's theory, one gets puzzling contradictions, an indication that one or both theories must be substantially revised before they can co-exist. The search for a consistent theory of "quantum gravity" unifying the laws of the very small with those of the very large, is currently one of the most important tasks confronting modern physics.
The purpose of this talk is to give an overview of Einstein's gravity and black holes, and then to show how black holes are playing such a vital role in this quest for a unified theory of quantum mechanics and gravity.
The outline of the talk is given on the next slide.